The present invention relates to a belt conveyor member having a widthwise central portion and a widthwise end portion which are provided with different contact surfaces in contact with a cleaning blade.
A full-color image forming apparatus using an intermediate transfer system is configured to obtain a color image by provisionally transferring a plurality of toner images that are formed on respective image bearing members on a color-by-color basis onto an intermediate transfer belt in such a manner that the toner images are superimposed on one another and then collectively transferring the toner images onto a recording medium such as a paper sheet. The transfer from the image bearing members to the intermediate transfer belt is called the “primary transfer”, while the transfer from the intermediate transfer belt to the recording medium is called the “secondary transfer”.
In the secondary transfer process, in particular, a secondary transfer roller is pressed against the intermediate transfer belt bearing the toner images across the recording medium, while a bias is applied to the secondary transfer roller and the like to generate an electric field. By so doing, the toner images are secondarily transferred onto the recording medium.
In attempt to improve the image quality resulting from such a secondary transfer process, a proposal has been made of provision of one or more hard layers on a surface of the intermediate transfer belt (see Japanese Patent Laid-Open Publication No. 2007-017666 for example).
The technique disclosed in Japanese Patent Laid-Open Publication No. 2007-017666, however, raises a problem with the relationship between the endless belt and the cleaning blade. Specifically, in cases where the roughness of the belt surface fails to increase and hence remains low because of a failure to supply toner serving as a lubricant to the surface of the intermediate transfer belt, the degree of intimate contact between the endless belt surface and the cleaning blade increases to cause the load imposed on an edge portion of the cleaning blade to increase, thus raising problems including a deformation of the cleaning blade, a cleaning failure due to distortion of the cleaning blade, a degradation in image quality due to banding, and reversal of the cleaning blade.
With the foregoing problems in view, a feature of the present invention is to provide a belt conveyor member which is capable of avoiding an increase in the degree of intimate contact between the endless belt and the cleaning blade.